1. Technical Field:
This invention relates to fluid operated downhole hammers and in particular hammers of the reverse circulation type.
2. Background Information:
Reverse circulation hammers are designed to pass rock cuttings and detritus from ground formations being drilled through the center of the hammer in order that uncontaminated samples of the well formation being drilled are passed to the surface or outer atmosphere for collection without passing out through the annular space formed between the walls of the hole being drilled and the hammer and casing connecting the hammer to the drill machine at the surface.